On the role of special relativity in general relativity

Abstract

The existence of a definite tangent space structure (metric with Lorentzian signature) in the general theory of relativity is the consequence of a fundamental assumption concerning the local validity of special relativity. There is then at the heart of Einstein's theory of gravity an absolute element which depends essentially on a common feature of all the non‐gravitational interactions in the world, and which has nothing to do with space‐time curvature. Tentative implications of this point for the significance of the vacuum solutions in general relativity, and for the issue of quantising gravity, are briefly examined.